Reply to "comment on 'diamagnetism and cooper pairing above T _c in cuprates' "

We analyze recent torque measurements of the magnetization M_d vs magnetic field H in optimally doped YBa₂Cu₃O _7-y (OPT YBCO) to argue against a recent proposal by R. I. Rey that the magnetization results above T_c are consistent with Gaussian fluctuations. We find that despite its strong interlayer coupling, OPT YBCO displays an anomalous nonmonotonic dependence of M_d on H which represents direct evidence for the locking of the pair wave function phase θ_n at T_c and the subsequent unlocking by a relatively weak H. These unusual features characterize the unusual nature of the transition to the Meissner state in cuprate superconductors. They are absent in low-T_c superconductors to our knowledge. We also stress the importance of the vortex liquid state, as well as the profiles of the melting field H_m(T) and the upper critical field curve H_c2(T) in the T-H plane. Contrary to the claims of Rey, we show that the curves of the magnetization and the Nernst signal illustrate the inaccessibility of the H _c2 line near T_c. The prediction of the H_c2 line by Rey is shown to be invalid in OPT YBCO.